Effect of Sodium Nitrite Addition on the Corrosion Resistance of Manganese Phosphate Coating

2020 ◽  
Vol 25 (3) ◽  
pp. 43-50
Author(s):  
Kyong-Sub Min
Keyword(s):  
Corrosion Resistance ◽  
Sodium Nitrite ◽  
Coating Layer ◽  
Phosphate Coating ◽  
Nacl Solution ◽  
Cross Sectional ◽  
Manganese Phosphate ◽  
Eds Analysis ◽  
Phosphate Coatings ◽  
Main Components

This paper describes an effective metal finishing technology for obtaining manganese phosphate coatings on steel. In this study, the effect of sodium nitrite addition on the corrosion resistance of a manganese phosphate coating was investigated. The microstructure, surface morphology, and chemical composition were analyzed by FE-SEM, EDS, and XRD, while the cross-sectional images and thickness of the coating layer were analyzed by FIB. According to the results of the EDS analysis, the main components of the manganese phosphate coating were C, O, P, Mn, and Fe. The XRD results showed that (Mn,Fe)5H2(PO4)4 4H2O in the manganese phosphate coating layer was formed by a chemical reaction between manganese phosphate and elements in the underlying carbon steel. Additionally, electrochemical polarization testing was carried out in order to evaluate the corrosion protection properties of the manganese phosphate coating in a 3.5 wt.% NaCl solution. The corrosion resistance of the phosphate coating was remarkably improved by adding sodium nitrite.

Effect of Surface Roughness on Crystal Size of Manganese Phosphate Coating of Carbon Steel

2020 ◽  
Vol 20 (7) ◽  
pp. 4312-4317
Author(s):  
Ho-Young Kim ◽  
Young-Tai Noh ◽  
Jun-Hyuck Jeon ◽  
Young-Min Byoun ◽  
Ho-Sang Kang ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Carbon Steel ◽  
Crystal Size ◽  
Coating Layer ◽  
Phosphate Coating ◽  
Force Microscopy ◽  
Atomic Force ◽  
Manganese Phosphate ◽  
Phosphate Coatings ◽  
Effect Of Surface

In this study, the correlation between surface roughness of carbon steel and crystal size of manganese phosphate coatings has been investigated. The microstructure and surface morphology of the coatings were analyzed by SEM, XRD. The surface roughness test was carried out in order to calculate Ra value by atomic force microscopy (AFM). Also, the tribology property of manganese phosphate coating was tested by ball-on disk. XRD showed that (Mn,Fe)5H2(PO4)4·4H2O in manganese phosphate coating layer was formed by the chemical reaction between manganese phosphate and elements in carbon steel. Also, (Mn,Fe)5H2(PO4)4 · 4H2O was observed to be formed in all manganese phosphate conversion coating. With regard to the effects of surface roughness on manganese phosphate coatings, it can be seen that there is an increase of the crystal size on manganese phosphate coating as the surface roughness of carbon steel decreased. The increase of crystal size by the surface roughness had effect on the tribology property and electrochemical property. It was approved that friction coefficient of manganese phosphate coating is remarkably improved as the surface roughness of carbon steel become rough.

Study on the Growth and Corrosion Resistance of Manganese Phosphate Coatings on 25Cr2Ni4WA Alloy Steel

2012 ◽  
Vol 185 ◽  
pp. 73-76
Author(s):  
J. Hu ◽  
Liang Fang ◽  
J.H. Mao ◽  
L.B. Xie ◽  
J. He ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Alloy Steel ◽  
Phosphate Coating ◽  
Polarization Method ◽  
Manganese Phosphate ◽  
Phosphate Coatings ◽  
Increase Rate ◽  
Bare Steel ◽  
Phosphated Steel ◽  
Coating Weight

The growth process and corrosion resistance of the phosphate coating on 25Cr2Ni4WA alloy steel fabricated by a high temperature manganese phosphating were investigated by XRD, SEM, EDS and electrochemical polarization method, respectively. It is found that the phosphate coating consists of lots of close packed lump crystallites and mainly composed of (Mn,Fe)5H2(PO4)4·4H2O. The coating weight increased rapidly, and then the increase rate slowed down when phosphating process was carried for about 5 min. The corrosion potentials of the phosphated steel shifted positively about 250 mV than the bare steel, indicating that the phosphating can improve the corrosion resistance of the 25Cr2Ni4WA alloy steel.

scholarly journals Manganese Phosphatizing Coatings: The Effects of Preparation Conditions on Surface Properties

Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2585 ◽  
Author(s):  
Jakub Duszczyk ◽  
Katarzyna Siuzdak ◽  
Tomasz Klimczuk ◽  
Judyta Strychalska-Nowak ◽  
Adriana Zaleska-Medynska
Keyword(s):  
Corrosion Resistance ◽  
Polarization Resistance ◽  
Anodic Polarization ◽  
Activation Process ◽  
Phosphate Coating ◽  
Low Alloy Steel ◽  
Corrosion Properties ◽  
Guanidine Derivatives ◽  
Preparation Conditions ◽  
Manganese Phosphate

Manganese phosphate coating could be used to protect the surface of steel products. However, it is essential to determine the effects which process parameters, as well as the types of additives used, have on the efficiency of coating deposition. Thus, we present here a process of phosphatization of low-alloy steel (for 15 min at 95 °C) in manganese/nickel baths followed by a passivation process with the use of a silicon and zircon compounds. The microstructure and morphology of the surface were analyzed by SEM EDX and XRD methods. The obtained results showed that the manganese phosphate could be effectively formed at 95 °C in the solution containing nickel and guanidine derivatives. Anodic polarization of manganese coating was investigated in 0.5 M KCl by the analysis of polarization resistance. The effects of the activation process on corrosion properties of the coating have been examined. It was observed that an increased concentration of activating substances in the activation bath results in the enhancement of corrosion resistance.

Radiometric Study of Phosphate Coatings Formed on Steel in Pretreatment Baths★

CORROSION ◽  
1954 ◽  
Vol 10 (9) ◽  
pp. 285-288 ◽  
Author(s):  
THOMAS F. BOYD ◽  
MICHAEL GALAN ◽  
LEONARD MARKOWITZ
Keyword(s):  
Phosphoric Acid ◽  
Sodium Nitrite ◽  
Sodium Phosphate ◽  
Diammonium Phosphate ◽  
Phosphate Coating ◽  
Sodium Dichromate ◽  
Corrosion Resistant ◽  
Phosphate Coatings ◽  
Corrosion Resistant Coatings ◽  
Sodium Phosphates

Abstract An investigation has been made of the amount of phosphate coating formed on steel by various rustinhibiting solutions. The treatments used were phosphoric acid, phosphoric acid with sodium dichromate and sodium nitrite with diammonium phosphate and with sodium phosphates. No correlation was found between the amount of phosphate coating formed and corrosion resistance. The nature of the coating appears to be the significant factor. The most corrosion resistant coatings were formed by diammonium phosphate-sodium nitrite and sodium phosphate-sodium nitrite treatments, the least by phosphoric acid alone.

Characteristics and corrosion studies of zinc–manganese phosphate coatings on magnesium–lithium alloy

RSC Advances ◽  
2014 ◽  
Vol 4 (104) ◽  
pp. 59772-59778 ◽  
Author(s):  
Guixiang Wang ◽  
Nana Cao ◽  
Yangyang Wang
Keyword(s):  
Corrosion Resistance ◽  
Conversion Coatings ◽  
Lithium Alloy ◽  
Manganese Phosphate ◽  
Phosphate Coatings ◽  
Corrosion Studies

Zinc–manganese phosphate conversion coatings have been formed on magnesium–lithium alloy, enhancing the alloy's corrosion resistance.

scholarly journals Effect of Phosphating Temperature on Surface Properties of Manganese Phosphate Coating on HSLA Steel

2020 ◽  
Vol 22 (1) ◽  
pp. 55-61
Author(s):  
Jana Pastorkova ◽  
Martina Jackova ◽  
Filip Pastorek ◽  
Zuzana Florkova ◽  
Juliana Drabikova
Keyword(s):  
Surface Properties ◽  
Electrochemical Impedance ◽  
Hsla Steel ◽  
Electrochemical Corrosion ◽  
High Strength ◽  
Phosphate Coating ◽  
Nacl Solution ◽  
Optimal Temperature ◽  
Manganese Phosphate ◽  
Photo Documentation

A phosphating process modified for a high-strength low-alloy (HSLA) steel was performed at various temperatures and influence on the surface properties of the Domex steel covered by manganese phosphate (MnP) was investigated by electrochemical corrosion tests supported by a photo documentation performed by the SEM. Corrosion measurements were performed in 0.1M NaCl solution at 22±2 °C using electrochemical impedance spectroscopy and potentio-dynamic polarisation in order to obtain thermodynamic and kinetic corrosion characteristics and individual elements of equivalent circuits. It is that a temperature of the phosphating process has a very significant effect on protection properties of the created manganese phosphate coating on the Domex steel and needs to be strictly monitored. According to results of corrosion testing and surface morphology observations, the optimal temperature for the phosphating process on the tested Domex steel was chosen.

scholarly journals Study the effect of sodium nitrite as a green corrosion inhibitor for the sputter-deposited tungsten-based ternary alloys in 0.5 M NaCl solution

BIBECHANA ◽  
2014 ◽  
Vol 12 ◽  
pp. 1-12
Author(s):  
Durga Bhakta Pokharel ◽  
Dhruba Babu Subedi ◽  
Jagadeesh Bhattarai
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Inhibitor ◽  
Sodium Nitrite ◽  
Inhibition Mechanism ◽  
Standard Free Energy Change ◽  
Nacl Solution ◽  
Positive Direction ◽  
Resistance Property ◽  
Corrosion Resistance Property ◽  
Sputter Deposited

Effects of sodium nitrite on the corrosion resistance and mechanism of the sputter-deposited W-80Cr-10Zr and W-42Cr-5Ni alloys were studied using corrosion tests and open circuit potential (OCP) measurements in 0.5 M NaCl solution, open to air at 25ºC. The corrosion resistance property of the W-80Cr-10Zr and W-42Cr-5Ni alloys was enhanced by the use of environmental friendly corrosion inhibitor of sodium nitrite. Higher corrosion resistance property and passivation behavior was observed for the W-42Cr-5Ni alloy than that for the W-80Cr-10Zr alloy based on the corrosion rate and OCP measurements. Adsorption process obeyed Langmuir adsorption isotherm to explain the corrosion inhibition mechanism of the alloys by sodium nitrite solution. The standard free energy change of adsorption of sodium nitrite on the W-80Cr-10Zr and W-42Cr-5Ni alloys was found to be -23.70 KJ/mole and -23.38 KJ/mole, respectively which suggested that sodium nitrite is strongly adsorbed on the surfaces of the alloy surfaces by physical adsorption, not by the chemisorption. As a result the corrosion resistance property of the alloys was significantly increased with increasing the sodium nitrite concentration. From the OCP measurement, it is concluded that sodium nitrite acts as an anodic corrosion inhibitor, because the OCPs of the alloys in presences of the corrosion inhibitors were shifted to more positive direction with increasing the concentration of sodium nitrite in 0.5 M NaCl solution open to air at 25ºC.DOI: http://dx.doi.org/10.3126/bibechana.v12i0.11670BIBECHANA 12 (2015) 1-12

The influence of hexamethylenetetramine on the structure and corrosion resistance of phosphate coating on AZ31 magnesium alloy

2016 ◽  
Vol 63 (3) ◽  
pp. 161-165 ◽  
Author(s):  
Jiansan Li ◽  
Yali Li ◽  
Yanqin Chen ◽  
Jiawei Sun ◽  
Chunxiao Wang ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloys ◽  
Design Methodology ◽  
Energy Dispersive Spectrometry ◽  
Electrochemical Impedance ◽  
Phosphate Coating ◽  
X Ray Diffraction ◽  
Content Type ◽  
X Ray ◽  
Phosphate Coatings

Purpose This paper aims to report the influence of hexamethylenetetramine (HMTA) on phosphate coatings formed on AZ31 magnesium alloys. Design/methodology/approach These phosphate coatings were obtained by immersing magnesium alloys in phosphate baths with HMTA. The morphology and composition of the phosphate coatings were investigated via scanning electron microscopy, energy dispersive spectrometry and X-ray diffraction. Findings The phosphate coatings were mainly composed of CaHPO4·2H2O. The HMTA concentration in the phosphate bath influenced the crystallization and corrosion resistance of the phosphate coating. Originality/value The polarization curve shows that the anti-corrosion qualities of the phosphate coating were optimal when the HMTA concentration was 1.0 g/L in the phosphate bath. Electrochemical impedance spectroscopy (EIS) shows that the electrochemical impedances increased gradually when the HMTA concentration varied from 1.0 to 3.0 g/L.

Effect of Phosphating Additives on Corrosion Resistance of Phosphate Coatings on AZ91D Magnesium Alloy

2011 ◽  
Vol 337 ◽  
pp. 112-115 ◽  
Author(s):  
Bi Lan Lin ◽  
Yu Ye Xu ◽  
En Cai Li
Keyword(s):  
Corrosion Resistance ◽  
Sodium Fluoride ◽  
Open Circuit Potential ◽  
Corrosion Potential ◽  
Zinc Nitrate ◽  
Open Circuit ◽  
Nacl Solution ◽  
Tafel Polarization ◽  
Phosphate Coatings ◽  
Corrosion Behaviors

AZ91D magnesium alloys were immersed in different phosphating solutions with zinc nitrate and sodium fluoride additives to enhance the corrosion resistance. The devolution law of the Open Circuit Potential (OCP) of AZ91D alloys during phosphating was measured. The corrosion behaviors of AZ91D alloys in 3.5%NaCl solution were investigated using OCP and Tafel polarization methods, and the effect of phosphating additives was discussed. The results show that the changes of the OCP of AZ91D alloys with phosphating time in different phosphating solutions are different; the anodic and cathodic corrosion processes of AZ91D alloys are conspicuously inhibited with phosphate coatings; zinc nitrate and sodium fluoride are benefit to form phosphate coatings with better corrosion resistance. The corrosion potential of AZ91D alloy phosphated in solutions with both zinc nitrate and sodium fluoride is most positive.

Effect of under layer metallic coating composition on phosphating and the corrosion performance for automobile applications

CORROSION ◽  
10.5006/3748 ◽  
2021 ◽  
Author(s):  
Chandrashekhar Savant ◽  
Poorwa Gore ◽  
VS Raja
Keyword(s):  
Corrosion Resistance ◽  
Electrochemical Impedance ◽  
Zinc Coating ◽  
Organic Coating ◽  
Phosphate Coating ◽  
Corrosion Performance ◽  
Epoxy Primer ◽  
Phosphate Coatings ◽  
Galvanized Coating ◽  
Salt Fog

Automobile coating system consists of a metallic underlayer followed by a phosphate coating and, lastly, multilayer organic coating. In this work, the effect of the underlying metallic coatings, namely, a Mg-Al-Zn alloy coating (Magizinc) and a conventional galvanized Zn coating on the phosphate coatings formed thereon, and its corrosion performance was investigated. The corrosion resistance offered by the phosphate coating formed on the Magizinc coating was higher than the phosphate coating on the galvanized Zn coating (a reference coating employed in the study) in NaCl solution, as revealed by potentiodynamic polarization, electrochemical impedance spectroscopy, and salt-fog tests. In-depth characterization of the phosphate coatings was carried out using scanning electron microscopy and glow discharge optical emission spectroscopy. It was revealed that the phosphate crystals formed on the Magizinc coating were more fine-grained, compact, and crack-free as compared to that formed on the galvanized coating and contained Mg aiding 4-10 times increase in the corrosion resistance as determined by the electrochemical studies. However, it only improved marginally against the appearance of red rust in a salt-fog test over the unphosphated Magizinc coating. The phosphate coating on Magizinc marginally improved the adhesion of an epoxy primer coating applied on the phosphated Magizinc coating and significantly (>3.5 times longer exposure) retarded the deterioration of the epoxy primer coating in the salt-fog environment in comparison with the similar studies carried out on the phosphated conventional galvanized zinc coating. Notably, phosphating the Magizinc coating caused a ten times reduction in the H pickup compared to that in the galvanized coating under identical phosphating conditions, suggesting the former coating lowered the propensity for hydrogen embrittlement in the steel.

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